metrics: transition all metrics to using metricsgen generated constructors. (port of #8488) (#9178)

This pull request completes the change to the `metricsgen` metrics. It adds `go generate` directives to all of the files containing the `Metrics` structs.

Using the outputs of `metricsdiff` between these generated metrics and `main`, we can see that there is a minimal diff between the two sets of metrics when run locally. The diff here stems from removal of the word 'message' which was done in v0.36+ and is ultimately a better phrasing. This metric has not yet been released, so this phrasing is preferred.

```
./metricsdiff old new
Metric changes:
+++ tendermint_consensus_full_prevote_delay
+++ tendermint_consensus_quorum_prevote_delay
--- tendermint_consensus_full_prevote_message_delay
--- tendermint_consensus_quorum_prevote_message_delay
```

This change also adds parsing for a `metrics:` key in a field comment. If a comment line begins with `//metrics:` the rest of the line is interpreted to be the metric help text. Additionally, a bug where lists of labels were not properly quoted in the `metricsgen` rendered output was fixed.

In my view, docs and tests are not needed for this internal only change.

---
#### PR checklist

- [ ] Tests written/updated, or no tests needed
- [ ] `CHANGELOG_PENDING.md` updated, or no changelog entry needed
- [ ] Updated relevant documentation (`docs/`) and code comments, or no
      documentation updates needed

Ports #8488 to main

p2p/metrics.gen.go

@@ -0,0 +1,58 @@
+// Code generated by metricsgen. DO NOT EDIT.
+
+package p2p
+
+import (
+	"github.com/go-kit/kit/metrics/discard"
+	prometheus "github.com/go-kit/kit/metrics/prometheus"
+	stdprometheus "github.com/prometheus/client_golang/prometheus"
+)
+
+func PrometheusMetrics(namespace string, labelsAndValues ...string) *Metrics {
+	labels := []string{}
+	for i := 0; i < len(labelsAndValues); i += 2 {
+		labels = append(labels, labelsAndValues[i])
+	}
+	return &Metrics{
+		Peers: prometheus.NewGaugeFrom(stdprometheus.GaugeOpts{
+			Namespace: namespace,
+			Subsystem: MetricsSubsystem,
+			Name:      "peers",
+			Help:      "Number of peers.",
+		}, labels).With(labelsAndValues...),
+		PeerReceiveBytesTotal: prometheus.NewCounterFrom(stdprometheus.CounterOpts{
+			Namespace: namespace,
+			Subsystem: MetricsSubsystem,
+			Name:      "peer_receive_bytes_total",
+			Help:      "Number of bytes received from a given peer.",
+		}, labels).With(labelsAndValues...),
+		PeerSendBytesTotal: prometheus.NewCounterFrom(stdprometheus.CounterOpts{
+			Namespace: namespace,
+			Subsystem: MetricsSubsystem,
+			Name:      "peer_send_bytes_total",
+			Help:      "Number of bytes sent to a given peer.",
+		}, labels).With(labelsAndValues...),
+		PeerPendingSendBytes: prometheus.NewGaugeFrom(stdprometheus.GaugeOpts{
+			Namespace: namespace,
+			Subsystem: MetricsSubsystem,
+			Name:      "peer_pending_send_bytes",
+			Help:      "Pending bytes to be sent to a given peer.",
+		}, labels).With(labelsAndValues...),
+		NumTxs: prometheus.NewGaugeFrom(stdprometheus.GaugeOpts{
+			Namespace: namespace,
+			Subsystem: MetricsSubsystem,
+			Name:      "num_txs",
+			Help:      "Number of transactions submitted by each peer.",
+		}, labels).With(labelsAndValues...),
+	}
+}
+
+func NopMetrics() *Metrics {
+	return &Metrics{
+		Peers:                 discard.NewGauge(),
+		PeerReceiveBytesTotal: discard.NewCounter(),
+		PeerSendBytesTotal:    discard.NewCounter(),
+		PeerPendingSendBytes:  discard.NewGauge(),
+		NumTxs:                discard.NewGauge(),
+	}
+}

p2p/metrics.go

@@ -2,9 +2,6 @@ package p2p
 
 import (
 	"github.com/go-kit/kit/metrics"
-	"github.com/go-kit/kit/metrics/discard"
-	"github.com/go-kit/kit/metrics/prometheus"
-	stdprometheus "github.com/prometheus/client_golang/prometheus"
 )
 
 const (
@@ -13,6 +10,8 @@ const (
 	MetricsSubsystem = "p2p"
 )
 
+//go:generate go run ../scripts/metricsgen -struct=Metrics
+
 // Metrics contains metrics exposed by this package.
 type Metrics struct {
 	// Number of peers.
@@ -26,56 +25,3 @@ type Metrics struct {
 	// Number of transactions submitted by each peer.
 	NumTxs metrics.Gauge
 }
-
-// PrometheusMetrics returns Metrics build using Prometheus client library.
-// Optionally, labels can be provided along with their values ("foo",
-// "fooValue").
-func PrometheusMetrics(namespace string, labelsAndValues ...string) *Metrics {
-	labels := []string{}
-	for i := 0; i < len(labelsAndValues); i += 2 {
-		labels = append(labels, labelsAndValues[i])
-	}
-	return &Metrics{
-		Peers: prometheus.NewGaugeFrom(stdprometheus.GaugeOpts{
-			Namespace: namespace,
-			Subsystem: MetricsSubsystem,
-			Name:      "peers",
-			Help:      "Number of peers.",
-		}, labels).With(labelsAndValues...),
-		PeerReceiveBytesTotal: prometheus.NewCounterFrom(stdprometheus.CounterOpts{
-			Namespace: namespace,
-			Subsystem: MetricsSubsystem,
-			Name:      "peer_receive_bytes_total",
-			Help:      "Number of bytes received from a given peer.",
-		}, append(labels, "peer_id", "chID")).With(labelsAndValues...),
-		PeerSendBytesTotal: prometheus.NewCounterFrom(stdprometheus.CounterOpts{
-			Namespace: namespace,
-			Subsystem: MetricsSubsystem,
-			Name:      "peer_send_bytes_total",
-			Help:      "Number of bytes sent to a given peer.",
-		}, append(labels, "peer_id", "chID")).With(labelsAndValues...),
-		PeerPendingSendBytes: prometheus.NewGaugeFrom(stdprometheus.GaugeOpts{
-			Namespace: namespace,
-			Subsystem: MetricsSubsystem,
-			Name:      "peer_pending_send_bytes",
-			Help:      "Number of pending bytes to be sent to a given peer.",
-		}, append(labels, "peer_id")).With(labelsAndValues...),
-		NumTxs: prometheus.NewGaugeFrom(stdprometheus.GaugeOpts{
-			Namespace: namespace,
-			Subsystem: MetricsSubsystem,
-			Name:      "num_txs",
-			Help:      "Number of transactions submitted by each peer.",
-		}, append(labels, "peer_id")).With(labelsAndValues...),
-	}
-}
-
-// NopMetrics returns no-op Metrics.
-func NopMetrics() *Metrics {
-	return &Metrics{
-		Peers:                 discard.NewGauge(),
-		PeerReceiveBytesTotal: discard.NewCounter(),
-		PeerSendBytesTotal:    discard.NewCounter(),
-		PeerPendingSendBytes:  discard.NewGauge(),
-		NumTxs:                discard.NewGauge(),
-	}
-}